The metal nanowires which have been synthesized by the porous anodic alumina (PAA)templates have excellent wire-grid structures

high transmittance and extinction ratio in the near infrared region.Therefore

the porous alumina with metal nanowires can be used as a near-infrared micropolarizer.Although this kind of micropolarizer has many advantages of smaller volume

simpler fabrication method and higher extinction ratio

its extinction ratio could not meet the requirement of the practical application. Based on the polarization principle of the metal wire-grid polarizer

we have analyzed the polarizing me-chanism of PAA with metal nanowires thoroughly.The reason why PAA films with metal nanowires have the properties of polarization is that the loss mechanisms to the

P

and

S

light components are different.Then

the metal nanowires with branched structure have been studied

and it could improve the extinction ratio of this kind of micropolarizers by using this branched structure. PAA alumina templates with branches structure were fabricated by the two-step anodic oxidation processes

and then the branched Cu nanowires were synthesized in the templates by alternating current deposition method.We observed the structure image of the samples by scanning electron microscopy

and measured the transmission spectrum and the polarization spectrum of the samples by the spectrophotometer.The transmittance of the Y-branched PAA template is achieved to 90% in the near infrared region

which means that the Y-branched PAA can also be taken as the template of the micropolarizers in this region.The experiment indicated that

such PAA alumina films with branched Cu nanowires have better transmittance in the near infrared region

and an extinction ratio of 14～22 dB was obtained in this region.Owing to the simple processing techniques

the high efficiency and the low cost

this kind of micropolarizer would have a promising future in the field of photoelectricity integration.